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Genomic changes disrupting the expression of cyclin D3 are associated with aberrant growth of several human B-lymphoid malignancies. We demonstrate that the human diffuse large B-cell lymphoma (DLBCL), OCI-LY18 (LY18) expresses cyclin D3 but not cyclins D1 and D2. RNA interference was used to deplete cyclin D3 from LY18 cells. Surprisingly, knockdown of cyclin D3 did not inhibit pRb phosphorylation on cdk4/6- and cdk2-specific residues or measurably affect viability and proliferation. These results suggest that cyclin D3 is dispensable in LY18 cell proliferation and survival. Similar results were obtained following depletion of cyclin E. By contrast, combined knockdown of cyclins D3 and E had substantial consequences leading to G(1)-phase arrest and inhibition of proliferation. Whereas cell cycle distribution was not affected following individual depletion of cdk4, cdk6 or cdk2, the combined knockdown of cdk4 and cdk6 led to accumulation of LY18 cells in G(1)-phase of the cell cycle and inhibition of proliferation. Likewise treatment of LY18 cells with 2-Bromo-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione, a selective inhibitor of cdk4/6, led to inhibition of proliferation. Taken together, these results uncover a built-in redundancy with cyclins D3 and E for G(1)-S progression. Moreover these findings highlight the rationale for simultaneous disruption of cdk4/6 as a potential therapeutic cancer strategy.

Background: The cyclin D1 (CCND1) and cyclin D3 (CCND3) are frequently co-overexpressed in pancreatic ductal adenocarcinoma (PDAC). Here we examine their differential roles in PDAC., Results: CCND1 and CCND3 expression were selectively suppressed by shRNA in PDAC cell lines with expression levels of equal CCND1 and CCND3 (BxPC3), enhanced CCND1 (HPAC) or enhanced CCND3 (PANC1). Suppression of cell proliferation was greater with CCND3 than CCND1 downregulation. CCND3 suppression led to a reduced level of phosphorylated retinoblastoma protein (Ser795p-Rb/p110) and resulted in decreased levels of cyclin A mRNA and protein. A global gene expression analysis identified deregulated genes in D1- or D3-cyclin siRNA-treated PANC1 cells. The downregulated gene targets in CCND3 suppressed cells were significantly enriched in cell cycle associated processes (p < 0.005). In contrast, focal adhesion/actin cytoskeleton, MAPK and NF B signaling appeared to characterize the target genes and their interacting proteins in CCND1 suppressed PANC1 cells., Conclusions: Our results suggest that CCND3 is the primary driver of the cell cycle, in cooperation with CCND1 that integrates extracellular mitogenic signaling. We also present evidence that CCND1 plays a role in tumor cell migration. The results provide novel insights for common and differential targets of CCND1 and CCND3 overexpression during pancreatic duct cell carcinogenesis.

Recent studies indicate that immune-associated aplastic anemia (AA) resembles such autoimmune diseases as insulin-dependent diabetes and chronic autoimmune thyroiditis that belong to organ-specific autoimmune diseases. Many independent investigation groups have successfully isolated the pathopoiesis-associated T cell clone causing hematopoiesis failure with a CD4 phenotype from peripheral blood and bone marrow (BM) in AA patients. In the current study, BM CD4(+) T cells were isolated from AA patients and healthy controls with immunomagnetic beads sorting, and proliferation capability, apoptosis features and the impacts of their secreted cytokines on hematopoiesis stem/progenitor cells were compared between them. By (3)H-TdR method, CD4(+) T cells in AA group presented more enhanced proliferative activity. The stimulation index in control group and AA group was 1.47+/-0.24, and 2.51+/-0.34 respectively (P<0.01). After BM CD4(+) T cells were induced by high concentration of CD3 monoclonal antibody for 18 h, evident apoptosis cells could be seen under the electron microscope in both control group and AA group. Flow cytometry revealed that apoptosis rates in the early and late stages of AA group were significantly higher than in control group (P<0.01). Early-stage apoptosis rate in control and AA groups was (6.85+/-1.48)% and (16.98+/-4.40)%, and late-stage apoptosis rate in control group and AA group was (2.65+/-1.57)% and (7.74+/-0.83)%, respectively (P<0.01). The CFU-GM count in AA group and control group was (74.50+/-9.50)/10(4) cells and (124.25+/-19.80)/10(4) cells respectively under an inverted microscope (P<0.01), and the expression levels of CyclinD3 mRNA and protein in cord blood CD34(+) cells were both down-regulated induced by BM CD4(+) T cell culture supernatant in AA patients. These results indicate that BM CD4(+) T cells of AA patients are likely in an abnormally proliferative, and activated state which can correlate intimately with AA hematopoiesis damage. BM CD4(+) T cells in AA patients can secret some soluble cytokines that can inhibit proliferation of hematopoietic stem cells by suppressing the expression of Cyclin D3, resulting in hematopoiesis failure.

Background: In most somatic tissues, adult stem cells are crucial for the maintenance of tissue homeostasis under normal physiological states and during recovery from injuries. Label retaining cell (LRC) assay remains the well-known method to identify possible somatic stem/progenitor cells and their location both in situ and in vivo., Methods: Here, BrdU was used to tag the possible hepatic stem/progenitor cells (HSPCs) in newborn pups, followed by a trace period of up to 23 months. Additionally, we report a method to rapidly kill proliferating cells in adult liver tissue, and activate and label (KAL) surviving possible HSPCs., Results: We found that LRCs definitively exist in the liver tissues of adult mice, that LRCs express cell cycle proteins cyclind3 and cdk6, but do not express sca-1 or c-kit, and that LRCs locate primarily in the periportal and pericentral regions. Moreover, the number of these LRCs remains nearly constant during the lifespan of the mice. After injury induced by 5-fluorouracil, we observed that the activation of possible HSPCs tagged by the BrdU label was almost completely inhibited at day 4. The cellular kinetics of repair of BrdU-tagged HSPCs were different every 12 h between day 3 and day 4. Moreover, HSPCs still retained labels and located definitively in the periportal region after a prolonged chase., Conclusions: The LRC method together with our novel KAL method reported here may be used to identify and locate possible HSPCs.

Background: Thyroid fine-needle aspiration (FNA) samples that feature a follicular-patterned, monotonous Hurthle (oncocytic) cell population cannot be diagnosed reliably. The authors of this report recently identified cyclin D3 overexpression on histologic sections of Hurthle cell carcinoma. In this study, they assessed the diagnostic value of cyclin D3 immunohistochemistry added to routine cytology., Methods: Fifty-one FNA samples that were suspicious for Hurtle cell neoplasia and that had histologic follow-up (19 malignant cases) were examined. Cyclin D3 expression levels were evaluated in cell block preparations and were compared with levels of the closely related cyclin D1 protein., Results: Greater than 25% positive cells were used as the cutoff point, as suggested by previous studies. Cyclin D1 and cyclin D3 were highly specific (100% for both) and fairly accurate (75% and 92%, respectively) in distinguishing between benign and malignant oncocytic lesions; the positive predictive value (PPV) for each was 100%. However, both cyclins D1 and D3 had low sensitivity (32% and 79%, respectively) and low negative predictive value (NPV) (71% and 89%, respectively). In contrast, by adopting balanced receiver operating characteristic-derived positive cutoff values, cyclin D1 (>or=6.5%) and cyclin D3 (>or=7.5%) were found to be highly sensitive (100% for both) and accurate (90% and 94%, respectively); and the NPV was 100% for both. In contrast, cyclins D1 and D3 had low specificity (84% and 91%, respectively) and a low PPV (79% and 86%, respectively); however, these values improved in samples that were positive for both cyclins (sensitivity, 100%; specificity, 94%; PPV, 90%; NPV, 100%; and accuracy, 96%)., Conclusions: Cyclin D3 increased the suspicion of malignancy in indeterminate oncocytic lesions; its diagnostic performance depended on the cutoff point used and was enhanced further when combined with cyclin D1., ((c) 2009 American Cancer Society.)

Approximately 10-15% of the human prion disease is inherited and one of the important genetic mutations occurs in the octapeptide repeat region of prion protein gene. One of the variants, one octapeptide repeat deletion (1-OPRD), existed in several gastric cancer cell lines and its mutation frequency was higher in gastric cancer cases. However, the biological functions of it remain unknown. Wild-type and mutation forms of PrP(C) were cloned and transfected into gastric cancer cells. Cell apoptosis, adhesion, invasion, multidrug resistance (MDR) and proliferation were, respectively, investigated. Different expressed genes were screened by gene array and proved by PT-PCR. Further, luciferase report assay was used to explore the transcriptional activation of target genes. Forced overexpression PrP(C) (1-OPRD) could promote the gastric cancer cells SGC7901 growth through facilitating G1- to S-phase transition in the cell cycle. PrP(C) (1-OPRD) could also inhibit apoptosis, and promote adhesion, invasion and MDR in SGC7901. However, it exhibited no significant difference between wild-type PrP(C) (1-OPRD) and PrP(C) on apoptosis, invasion or MDR effects. Further experiments indicated that PrP(C) (1-OPRD) could trigger the transactivation of cyclinD3 besides cyclinD1 to promote cell transition and proliferation. Overexpression of PrP(C) (1-OPRD) might promote the proliferation of gastric cancer cells at least partially through transcriptional activation of cyclinD3 to accelerate the G1-/S-phase transition. The promoting proliferation effect of PrP(C) (1-OPRD) was more than that of wild-type PrP(C). However, they showed no difference on apoptosis, adhesion, invasion or MDR effects of gastric cancer cells.

Neurofibromatosis type 1 (NF1) microdeletion is a large genomic deletion that embraces at least 11 continuous genes at human chromosome 17q11.2. To date, most of these genes' functions still remain undefined. In this study, we report an unknown cytokine receptor like molecule (p48.2) that is frequently deleted in patients with type-1 and type-2 NF1 microdeletions in the neurofibromin locus. The cloned gene has 1317 base pair long that encodes a 438aa intracellular protein. The gene was subsequently named p48.2 based on its predicted molecular weight. A typical fibronectin type III (FNIII) domain was identified in p48.2 between Arg(176) and Pro(261) in which a palindromic Arg-Gly-Asp (RGD) repeat plus a putative Trp-Ser-X-Trp-Ser (WSXWS) motif were found at the domain's C-terminus. p48.2 mRNAs were abundant in many tumor cell lines and normal human tissues and up-regulated in some freshly isolated lung cancer and leukemia cells. Interestingly, over-expression of p48.2 in human embryo kidney 293T cells could significantly cause G0/G1 arrest and prevented S phase entry. In contrast, repressing endogenous p48.2 gene expression by specific siRNA markedly reduced G0/G1 population. Importantly, over-expression of p48.2 could significantly up-regulate rather than down-regulate cyclin D1 and cyclin D3 expressions. We further showed that the induction of cyclin D1 expression was directly due to the activation of signal transducers and activators of transcription 3 (STAT3), but was independent of RAS/mitogen-activated protein kinase (RAS/MAPK) signaling pathway. Thus, p48.2 may represent a novel type of intracellular protein functioning as a negative regulator at the G0/G1 phase.

The effect of mammalian target of rapamycin (mTOR) inhibitors on pituitary tumors is unknown. Akt overexpression was demonstrated in pituitary adenomas, which may render them sensitive to the anti-proliferative effects of these drugs. The objective of the study was to evaluate the anti-proliferative efficacy of the mTOR inhibitor, rapamycin, and its orally bioavailable analog RAD001 on the GH-secreting pituitary tumor GH3 and MtT/S cells and in human GH-secreting pituitary adenomas (GH-omas) in primary cell cultures. Treatment with rapamycin or RAD001 significantly decreased the number of viable cells and cell proliferation in a dose- and time-dependent manner. This was reflected by decreased phosphorylation levels of the downstream mTOR target p70S6K. Rapamycin treatment of GH3 cells induced G0/G1 cell cycle arrest. In other tumor cell types, this was attributed to a decrease in cyclin D1 levels. However, rapamycin did not affect cyclin D1 protein levels in GH3 cells. By contrast, it decreased cyclin D3 and p21/CIP, which stabilizes cyclin D/cyclin-dependent kinase 4 (cdk4) complexes. Rapamycin inhibited FCS-induced retinoblastoma phosphorylation and subsequent E2F-transcriptional activity. In response to decreased E2F activity, the expression of the E2F-regulated genes cyclin E and cdk2 was reduced. Our results showed that mTOR inhibitors potently inhibit pituitary cell proliferation, suggesting that mTOR inhibition may be a promising anti-proliferative therapy for pituitary adenomas. This therapeutic manipulation may have beneficial effects particularly for patients harboring invasive pituitary tumors resistant to current treatments.

Hyperglycemia is one of the factors that induces autophagy. Our recent studies demonstrate that dividing cells in hyperglycemic medium initiate an intracellular stress response that involves synthesis of hyaluronan and its extrusion extracellularly into structures that are recognized by inflammatory cells. During the later phase, a complex with cyclin D3, CDK4 and C/EBPalpha was observed in the hyperglycemic cultures, and cyclin D3 and C/EBPalpha colocalized in coalesced perinuclear honeycomb-like structures with embedded hyaluronan. Further, microtubule-associated protein 1 light chain 3 (LC3), a marker for autophagy, colocalizes with these structures. These results suggest that cyclin D3 is a central coordinator that controls the organization of a complex set of proteins that regulate autophagy and subsequent formation of the monocyte-adhesive hyaluronan matrix. However, the early intracellular accumulation of hyaluronan could have a critical role in initiating or regulating these downstream events.

Background/aims: Glomerular hypertrophy is a feature of many glomerular diseases and is associated with the development of renal failure. We previously demonstrated that the cyclooxygenase 2 inhibitor, NS398, reduced glomerular size after uninephrectomy. Thus, we hypothesized that prostaglandin (PG) E(2) would cause mesangial cell hypertrophy in vitro., Methods: We used a mesangial cell line and primary culture of rat mesangial cells. The effects of PGE(2) on mesangial cell hypertrophy were determined using immunohistochemistry and image analysis to assess cell size, 3H-leucine incorporation as a measure of protein synthesis and flow cytometry to assess cell cycle status. Western blot was used to examine the effect of PGE(2) on expression of cyclin D3, p15, p27 and cyclin-dependent kinase 4--known regulators of the cell cycle., Results: PGE(2) increased cell size by 13% and protein synthesis (3H-leucine incorporation) by 35% over 24 h. By flow cytometry, PGE(2) increased the percentage of cells in G0/G1 phase of the cell cycle from 70.13 +/- 1.01 to 74.06 +/- 1.18% and conversely, decreased the number of cells in S phase from 24.07 +/- 1.06 to 22.03 +/- 0.78%. The number of cells in G2/M was also reduced. Expression of cyclin D3 was decreased by 60% after treatment with PGE(2), while expression of p27 was increased. The effects of PGE(2) on cell size and flow cytometry were reproduced by the prostaglandin E(2) receptors EP1/EP3 agonist sulprostone., Conclusion: PGE(2) induces mesangial cell hypertrophy and cell cycle arrest via its EP1 receptor., (Copyright 2009 S. Karger AG, Basel.)

The anti-cancer effects of betulinic acid (BA) on Jurkat cells and its in vitro mechanism were examined by using MTT assay. Apoptosis was detected by using Hoechst33258 staining and annexin-V/PI double-labeled cytometry. The effects of betulinic acid on the cell cycle of Jurkat cells were studied by propidium iodide method. RT-PCR and Western blotting were used to analyze the changes of cyclin D3, bcl-xl mRNA and protein levels in Jurkat cells after treatment with betulinic acid. Our results showed the proliferation of Jurkat cells was decreased in betulinic acid-treated group with a 24-h IC50 value being 70.00 mumol/L. Betulinic acid induced apoptosis of Jurkat cells in a time- and dose-dependent manner. The number of Jurkat cells treated with betulinic acid showed an increase in G(0)/G(1) phase and decrease in S phase. After treatment with 0, 20, 60, 100 mumol/L betulinic acid for 24 h, the number of Jurkat cells was increased from (31.00+/-1.25)% to (58.84+/-0.32)% in G(0)/G(1) phase, whereas it was decreased from (61.45+/-1.04)% to (35.82+/-1.95)% in S phase. PBMCs were less sensitive to the cytotoxicity of betulinic acid than Jurkat cells. The expressions of cyclin D3, bcl-xl mRNA and protein were decreased sharply in Jurkat cells treated with betulinic acid. It is concluded that betulinic acid is able to inhibit the proliferation of Jurkat cells by regulating the cell cycle, arrest cells at G(0)/G(1) phase and induce the cell apoptosis. The anti-tumor effects of betulinic acid are related to the down-regulated expression of cyclin D3 and bcl-xl.

Objective: To investigate the anticancer effects of betulinic acid (BA) on Jurkat cells in vitro and its molecular mechanism., Methods: The effects of betulinic acid on the growth of Jurkat cells were studied by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5diphenyl-2H-tetrazolium (MTT) assay. Apoptosis was assessed by Hoechst33258 staining and annexin-V/PI double-labeled cytometry. The effect of betulinic acid on the cell cycle of Jurkat cells was studied by propidium iodide staining. RT-PCR and Western blot were used to analyze the changes of cyclin D3, bcl-xl mRNA and protein levels in Jurkat cells after treatment with betulinic acid., Results: The proliferation of Jurkat cells was decreased in betulinic acid-treated group at a 24 h IC50 value of 70.0 micromol/L. The effect of betulinic acid to induce apoptosis in Jurkat cells was in a time- and dose-dependent manner. Jurkat cells treated with betulinic acid showed an increase of G0/G1 phase and decrease of S phase. The Jurkat cells treated with 0, 20, 60, 100 micromol/L betulinic acid for 24 h, showed an increased G0/G1 phase from 31.0% to 58.8%, whereas decreased S phase from 61.5% to 35.8%, respectively. PBMC was less sensitive to the cytotoxic effect of betulinic acid than Jurkat cells. The expression of cyclin D3, bcl-xl mRNA and protein were decreased sharply in Jurkat cells treated with betulinic acid., Conclusion: Betulinic acid can inhibit the proliferation of Jurkat cells by regulating the cell cycle that arrests cells at G0/G1 phase and induces apoptosis in Jurkat cells. The antitumor effects of betulinic acid may be related to down-regulation of the expression of cyclin D3 and bcl-xl.

Background & Objective: No serum starvation could induce autophagy and cell cycle arrest. Although autophagy and cell cycle have been widely explored, little is known about their relationship. This study was to observe the change of Cyclin expression during starvation-induced autophagy to discuss the effect of autophagy on cell cycle., Methods: In control group, HeLa cells were treated with d-Hanks solution (a medium with no serum). In experiment group, HeLa cells were treated with d-Hanks solution containing 3-methyladenine (3-MA, a specific inhibitor of autophagy). Cells were harvested after being starved for 0, 3, 6 and 12 h. Flow cytometry (FCM) and Weston blot were used to detect Cyclin and microtubule-associated protein 1 light chain 3(LC-3) which marked autophagy specifically., Results: In control group, the expression of LC-3 protein was detected early after being starved for 3 h, and gradually increased along with starvation; the expression of Cyclin D3 and Cyclin E was decreased evidently after a short-time starvation (3 h) and descended to the minimum when cells were being starved for 6 h; the expression of Cyclin A and Cyclin B1 were apparently decreased after being starved for 6 h. In experiment group, LC-3 protein could not be detected during starvation when cells were exposed to 3-MA and the down-regulation of Cyclins was suppressed., Conclusions: Autophagy is involved in starvation-induced hydrolysis of Cyclins. The hydrolysis of Cyclin D3 and Cyclin E is quicker than that of Cyclin A and Cyclin B1.